<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="./css/index.css">
    <title>Notepad</title>
</head>
<body>
    
<!-- 主体区域 -->
<section id="app">
    <!-- 输入框 -->
    <header class="header">
      <h1>小黑记事本</h1>
      <input placeholder="请输入任务" class="new-todo" v-model.trim="todoName" @keyup.enter="add()"/>
      <button class="add" @click="add()">添加任务</button>
    </header>
    <!-- 列表区域 -->
    <section class="main">
      <ul class="todo-list">
        <li class="todo" v-for="(item, index) in list" :key="item.id">
          <div class="view">
            <span class="index">{{ index+1 }}</span> <label>{{ item.name }}</label>
            <button class="destroy" @click="remove(item.id)"></button>
          </div>
        </li>
      </ul>
    </section>
    <!-- 统计和清空 -->
    <footer class="footer" v-show="list.length > 0">
      <!-- 统计 -->
      <span class="todo-count">合 计:<strong> {{ list.length }} </strong></span>
      <!-- 清空 -->
      <button class="clear-completed" @click="clear()">
        清空任务
      </button>
    </footer>
  </section>
  
  <!-- 底部 -->
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
  <script>
  
    const app = new Vue({
      el: '#app',
      data: {
        list:[
            {id:1, name:'俯卧撑100个'},
            {id:2, name:'跑步1000米'},
            {id:3, name:'足球15分钟'}
        ],
        todoName: ''
      },
      methods:{
        remove(id){
          this.list = this.list.filter(item => item.id !== id)
        },
        add(){
          if(this.todoName !== ''){
              // unshift在数组的开头添加一个或多个元素，push在数组的末尾添加一个或多个元素
              this.list.unshift({
              // 使用时间戳作为id值
              id: +new Date(),
              name: this.todoName
            })
            this.todoName = ''
          }else{
            alert("请输入任务名称")
          }
        },
        clear(){
          this.list = []
        }
      }
    })
  
  </script>
  </body>
  </html>
  